Is there anyone running a 518 transmission with 3.08s?

If so, how is your fuel mileage running empty?
How does it do with a load, say around 10K?

Thanks, Tom
Valley Center, Ks

 

i hope your not planning to be there in a hurry. If i was running a 518 w/ 3.08 it would be a commuter vehicle with even better with a 4bt

 

If I'm not mistaken the 518 1st 2nd and 3rd is the same ratio as the 727 trans the difference is the OD ratio and the extra gear. I will be running that set up hopefully by the end of the year. I am getting a best of 18 mpg's out of my 727 with 3.07 and I am hoping to get into the mid 20's once it's all said and done.

 

but not towing 10k

 

fuel mileage 21 plus under 70 empty. never grossed more than 14k with my 90. just dropped out of o.d. on the hills to help with trans temps.

 

My 93 dually ran around 20 MPG with OD and 3:08's empty.

With a 10k load I would run around 13 MPG. I hauled a load 775 miles at 70 MPH for this fuel figure.

RPM at 60 MPH is 1650 with 235/85/16R tires.

 

Thanks for the response guys!
I am already getting 20 mpg city and suburban driving now.
I just don't like the 80 mph top end and the high revs.
My pinon bearings are getting bad, and 308 gears are hard to come by in the case that I might have to replace the gears.
I might be parting out a 92 dually because of title problems and thought of using the 518 trans in the 90.

Again thanks for the interest.

Tom

 

Going to the 518 will make the truck a lot quiter at the speed limit. 1650 RPM at 60 MPH makes for a quite truck.

If you have the 518 all ready go for it. You will not be disappointed. Get those bearings replaced ASAP.

 

Arent the bearings the same between the 3.07 and 3.54/4.10? I had heard they were, but am not 100% sure.

 

The bearings are the same as far as I know.

I normaly don't buy the bearings till I have it apart. I just take the numbers off the bearings and races that are in it. Saves some headaches that way.